Several toilet structures have been known in the art. The difficulty with most conventional toilets of the type using water storage tank is that once a knob of the tank is operated to introduce water into the toilet bowl, the flush operation will not stop until all the water in the tank is used up. Quite often this is kind of waste, especially in those countries where water supply is in shortage. Also known is a toilet structure which is so designed that after flush operation is started by pressing a knob of the tank, the operation will not stop until the knob is released. In this way, one can control the volume of water required for flush purpose by pressing the knob for a desired period of time. However, this is obviously inconvenient for the user because he has to keep pressing the knob throughout the flush operation.
Another serious problem with conventional flush toilets is that the closure member for sealing the water in the water storage tank is planarly in contact with the outlet of the tank and thus will be worn out after a short period of time, thus causing undesirable water leakage from the tank into the toilet bowl.